The present disclosure generally relates to telecommunication, more specifically, to a method and system for enabling and facilitating inbound roaming of subscribers equipped with a mobile device such as a Long Term Evolution (LTE) device from a Home Public Land Mobile Network (HPLMN) that has no voice over LTE (VoLTE) services or the HPLMN is not VoLTE capable onto a Visited Public Land Mobile Network (VPLMN) which does not support Circuit Switched Fall Back (CSFB) but has a VoLTE capable network.
As telecommunication technology has progressed, numerous mobile communication standards have been developed. These standards are broadly categorized into second generation (2G), third generation (3G) and fourth generation (4G) technologies. Examples of 2G/3G technologies include Global System for Mobile communications (GSM), General Packet Radio Service (GPRS), Enhanced Data rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), and the like. The UMTS standard further evolved to Evolved Packet System (EPS) under the Third Generation Partnership Project (3GPP). LTE commonly denominates the 3GPP EPS as well as its Evolved-Universal Terrestrial Radio Access. LTE technology offers a wireless broadband system with higher data rates, lower latency, and higher spectrum efficiency, but doesn't provide any telephony services including voice or short message service.
The services such as voice or short message services are provided by two different 3GPP defined solutions. The first one has been designed as an intermediate solution and is called Circuit Switched Fall-Back (CSFB), which requires having a circuit switched network. The second solution is provided through implementing Intelligent Multimedia sub System (IMS) functionality. The GSM Association (GSMA) further defined a profile of IMS for a better inter-operability between Public Land Mobile Networks (PLMNs), which is called Voice over Long Term Evolution (VoLTE).
Some operators have launched a LTE system or network without having a GSM or an UMTS network because they operate a Code Division Multiple Access (CDMA) network or because they are new actors on the market and they only have a LTE license. CDMA network may implement a CDMA based version of CSFB. Green field operators which have only their new networks can only support VoLTE technology to provide voice and short message services under the 3GPP framework.
In essence, CSFB, CSFB CDMA version and VoLTE are not interoperable. Thus, before a wide adoption of GSMA's VoLTE technology by the mobile industry, LTE based VPLMNs that don't support GSM based CSFB implementation will not be able to provide voice services to roaming subscribers from a HPLMN that doesn't support VoLTE nor CDMA based CSFB (GSM is the dominant technology worldwide). As a consequence, those roaming subscribers or roamers will not be able to roam on a VoLTE only VPLMN and the later will lose potential wholesale revenues. Over the last few years, the revenues to network operators have consistently declined due to increased competition, resulting in pricing pressures. On the other hand, LTE subscribers are high average revenue per user (ARPU) roamers that could provide an increase of revenues to both the home and visited operators if LTE roaming is enabled. Hence, providing LTE subscribers access to the LTE radio network has become an important priority for the network operators worldwide.
Hence, there is a need in the art to have a system and method for enabling VoLTE services for non-VoLTE inbound roamers.